<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../react18/react.development.js"></script>
    <script src="../react18/react-dom.development.js"></script>
    <script src="../react18/babel.min.js"></script>
</head>

<body>
    <div id="app"></div>
    <script type="text/babel">
        class App extends React.Component{
            constructor(){
                super()
                //改变handle的this指向并把它放在组件实例中
                this.handle = this.handle.bind(this)
            }
            state = {
                count: 0
            }
            render() {
                const {count} = this.state
                return (
                    <div>
                        <button onClick={this.handle}>加加加</button>
                        <p>{count}</p>
                    </div>
                )
            }

            handle = function(){
                // console.log(this);//undefined,改变this指向,使其指向组件实例,从而拥有实例上的属性和方法
                //获取state身上的数据
                // this.state.count = 11//直接修改state不会调用也不会重新渲染

                // const {count} = this.state
                // count += 1//SyntaxError: Inline Babel script: "count" is read-only

                //利用setState方法可以控制state的状态
                const {count} = this.state
                this.setState({
                    count: count+1
                })
                  
            }
        }

        const root = ReactDOM.createRoot(document.getElementById("app"))
        root.render(<App />)
    </script>
</body>

</html>